Fertigation, yields make case for drip

But he's more than quadrupled yield potential after installing a sub-surface drip irrigation system. The system also allows Hampton to apply fertilizer and pesticides through the drip tape.

The first year he ran the drip irrigation system, 2001, the field averaged right at two bales. The next year, yields dropped when Hampton went to a conventional weed control program "so we could chop out some of the weeds."

This year, close to 1,200 pounds of cotton per acre were hanging on the plants by mid-September.

Hampton installed a drip system developed by Netafim Irrigation, Inc., because the field's shape and soil characteristics were not suitable for either furrow or center pivot irrigation.

The cost of the system was steep, projected for most systems at $700 to $1,000 per acre. Hampton absorbed the costs, but believes he'll make it back in improved yield and cost savings.

Any sub-surface drip system in the Missouri Bootheel must first address high iron content in the region's water, noted Hampton.

On Hampton's system, well water from a 400 gpm submersible pump flows through a chemigation check value — which protects the water source. It's then treated with chlorine and N-pHuric acid stored in two large tanks. "The acid helps correct the pH and provides a nitrogen source while the chlorine helps oxidize the iron so we can filter it out," Hampton said.

The water then runs through two large filters, then to an injector where P, K, micronutrients, or other chemicals can be added.

Fertigation and the application of pesticides through drip are the biggest benefits of the system for Missouri growers, according to Craig Pisarkiewicz, a dealer for the Fresno, Calif.-based Netafim.

In addition, there are significant water savings with drip, and the user should expect a much more efficient and responsive system, according to Pisarkiewicz. "As soon as you turn on the system, each plant is getting watered within a minute."

On the other hand, water savings are not as big a concern for Missouri growers, according to Joe Henggeler, irrigation engineer at the Delta Center in Portageville.

"A drip system is competing against cheap water in the Bootheel. In Texas (where drip systems are very popular), water is more expensive because there's not enough of it."

On Hampton's 70-acre field, drip tape is installed under every other middle, about 8 to 10 inches deep. The preferred depth is around 14 inches.

The every-other-middle approach still provides adequate moisture across the soil profile, according to Pisarkiewicz. "The key is high-frequency irrigation, not just turning it on and letting it run for 12 hours, but turning it off and on."

The high-frequency approach "never saturates the soil. It allows capillary action to take the water in every direction, so you get water up and across."

According to Jim Phene, district sales manager for Netafim, a drip system provides benefits in yield, fiber quality and earliness, too. "Sometimes, we can go to a full-season crop to gain some extra yield potential."

Hampton noted that the earliness benefit of drip helped him address a root-knot nematode problem on the drip field in 2003. He was able to plant a full-season variety, Stoneville's ST 5599 BR, which is resistant to the pest.

The Environmental Quality Incentives Program could defray up to 50 percent of the costs of drip installation, according to John Hester, a civil engineer with Natural Resources Conservation Service. Hester was on hand during a recent field day at the field.

For a drip irrigation cost-share bid to be accepted, a producer must have an existing irrigation system already in place and meet a number of other qualifications.

In a drip system, "What we're looking for is improving what's out there. EQIP will not pay for installing drip irrigation on a dryland field or for fertigation equipment," Hester said. "We'll pay on the tape itself and on the manifolds."